The invention relates to a method for the recognition of an edge of a magnetic medium and a device for implementation of the method.
As is known, information can be inscribed upon and read out from a magnetic medium, for example a magnetic disk or a magnetic tape, by means of generating magnetic flux changes. For this purpose, a read and write system, for example a magnetic head with a write and read gap, can be employed. During inscription, electric signals are converted into a change of the magnetic flux by means of induction at the write gap or, respectively, changes of magnetic flux on the medium are sensed at the read gap and are converted into electrical signals. In comparison to the surface of the medium, the write gap and the read gap can be small, so that a plurality of tracks which arise given movement of the medium past the gap, can be recorded. When these tracks are read, for example with a read and write system which differs from the one used for recording, it is essential that the read gap be precisely disposed over the track produced by the write head.
Given a magnetic tape, a method of aligning the read gap to the track recorded by the write gap consists of employing the edge of the magnetic tape as a reference. Already during recording, the write gap at the transition from one track to another is offset, proceeding from the edge, by a fixed track spacing. In the transition from one track to another, the read gap, proceeding from the edge, is likewise offset by this track spacing. The initial position of the write and read system at the reference point can be manually fixed, for example as a function of a tape guidance. However, it is a disadvantage that positional changes of the sensing system or of the tape guidance and manufacturing tolerances cannot be taken into consideration, since the adjustment is usually only undertaken once.